When a man does a good job performing oral sex on a woman, she will wrap her legs around his head, locking his lips against hers. If the lady's legs are wrapped tight enough, the man's air supply will be cut off causing him to suck harder to try to get air in his lungs, creating increased pleasure for the female.

I was going down on my girlfriend last night and she liked it so much, she put me in the Louisiana Lip Lock.